Gear testing machine



Jan. 7, 1936.- OLSON 2,026,649

GEAR TESTING MACHINE I Filed NOV. 22, 1953 4 Sheets-Sheet 1 /1s INVENTORCARL e; OLSON wt? Q 9 +4 I 4 ATTYS a 3 4 c. G. OLSON GEAR TESTINGMACHINE Filed Nov 22, 19s:

4 Sheets-She et 2' R O N E V N BY W ATTYS.

Jan. 7, 1936. c c; OLSON 2,026,649

GEAR TESTING MACHINE Filed .Nov. 22, 1933 4 Sheets-Sheet 5 x INVENTORCARL e. OLSON BY VW I ATT'Y$..

Jan. 7, 1936. v c. G; 0.5%

STING MACHINE Filed Nov. 22 1933 4 Sheets-Sheet 4 "Ii E "H I l wllllmINVENTOR UARL e. OLSON BY W V ATT'YS.

Patented J an. 7, 1936 UNITED s r-Ares p res-r; om n-z aozam em''rns'rnvd momma Carl G. 01m, Chicago, m,mto Illinois Tool Works,Chicago, 111., a, on of I Application November as, ms, Serial No.sea-11s it ow s. (or, 33-11;)

which make for increased accuracy in the testing of gears, and alsofacilitate the ease with culties .or disadvantages cf the fact. that thewhich such tests may be made. One of the difjil-.

v which has heretofore been experienced in connection with the use ofgear testing machines has been the introduction of errors resulting fromlateral displacement of the work or gear supporting spindle. Inview gearsupporting spindle must. of necessity, be coupled with the mechanismwhich correlates-the rotary movement of the gearblank and the straightline movement of a contactor, said spindle has been subjected to,lateral stresses because of inherent deficiencies in structural design.It is, therefore, one of theirnportant objects of the present inventionto provide a gear ,testing' machine whereby the above mentioned andother serious disadvantages here.- tcfore experienced may be completelyobviated. More specifically, it is an object of my invention to providea gear testing machine; of the type equipped with a master roller orcylinder corresponding in diameter with the diameter of the base circleof the gear, and in combination with said master cylinder, I propose toemploy frictional driving mechanism. which is adapted to impart positiverotation to the cylinder with out subjecting the gear supporting spindledriven by said cylinder, to lateral streses which would have atendencyto introduce errors.

Still-more specifically, it is an object of my invention to so couplethe peripheral surface of the base, circle cylinder with a reciprocableor tangentially movable driving member, that the force employed tomaintain frictional contact between said parts will be transmittedthrough the cylinder to the tangentially movable member withoutsubjecting the bearings of the work or gear supporting spindle to anyoverload conditions, which might have a tendency to eflect lateraldisplacement thereof. Y Further, my invention contemplates the provisionof a testing machine of the type set-forth above, wherein the workorfgear support, and spindle are floating, in thesense that the pres'sureexerted to makev the base circle cylinder roll on astraig'htsurface without sliding isnot tra ns-.

' an improv an improved,

I nism which serves mitted through the bearings of the workspindle, butthrough and by-a roller independent of said spindle. and. directlyengaging the periphery of the base cylinder. v V Another object ofmyinvention isto provide ed indicator device for indicating the theworkspindle, and to this an indicator member degreeof rotation of end Ipropose to provide coupled frictionally with the work-spindle andadapted to be shifted with respect to said spindle for purposes ofadiustmentn Still another object of the vide an improved reversibleindicatormechanism in combination with a contactor, one end of whichisadapted to make a point contact with the tooth of the gear,.and theopposite extremity invention is to pro- 1 of which is adapted forcoupling with an indicator mechanism, such for example, asa dial infdicator which serves to indicate variations, if

any. in the surface contour .of the teeth in the ac gear.

Another object of my invention is to provide- I compactly arrangedtesting ma chine which-necessitates relatively few parts, and which maybe economically manufactured by-the practice of conventional machineshop methods. The foregoing, and numerous other objects and'advantages'will be more apparent from the following detaileddescription when considered in connection with the accompanyingdrawings, so.

wherein Y Fig. 1 isa plan view of agear testing machine which isrepresentative of one embodiment of myinvention;

Fig. 2 is a-front elevational view of the machine shown in Fig. l, witha. portion ofthe upper structure broken away; Fig. 3 is a detailed planview 'of the mechato couple the gear to be tested with the base circlecylinder; I" 40 Fig. 4 is a central,vertical sectional view of thetesting machine,'i taken substantially along the line 4-4 of Fig. 1,theupper portion of the vertical and work .spindle being broken away;Fig. 5 is a detailed plan view of the indicator mechanism which-servesto indicate the degree of rotation of the work or gear, said view beingtaken substantially along the line 5-4! of Fig. 4; Fig.6 is atransversevertical sectional view of the machine taken substantially along theline r as clearly shown in Figures 1 and 4. The frame I2 is formed witha depending section I6, and

this section I6 houses a rotatable spindle supporting' sleeve mechanismI6, Figure 4. This mechanism includes a sleeve 26 adapted at its upperend to receive a tapered shank 22 of a spindle 24.

The sleeve 26 is freely rotatable withinspaced anti-friction bearings 26and 28, and a collar 36 serves to clamp the inner. races of the bearings26 and 28, a sleeve 32 and the spindle supporting sleeve 26 together asa rotary. unit.

The spindle 24 is provided with a flange-34 whichformsthe lower supportof a cylindrical member 36, which will hereinafter be referred to as thebase cylinder, for the reason that the di-- ameter of the cylindercorresponds with the diameter of the-base circle of a gear 36 to betested. The upper extremity of the spindle 24 terminates in a center 46,which receives the lower end-of .a gear or worksu'pporting spindle 42.The upper end of. the spindle 42 is designedto receive a center 44(Figure 2) which is carried by a tailstock device 46. I This tailstockdevice includes a housing 46 for-the spindle proper and a pair of arms-66 diverging therefrom, which terminate in sleeves 52. These sleeves62are slidable upon vertical posts or uprights 64. Verticafadiustment ofthe spindle supporting device 46 along the uprights 44 is occasioned bymanipulation of a handwheel 66. The hand-wheel 66 connects withmechanism which meshes with rack teeth 66 er 84. The roller.64.rollsalong the flat surface of a strip 86 mounted upon the front end of the(Figure 4) provided alongthe uprights 64 to cause vertical movement ofthe device 46.

Mechanism for coupling the base cylinder 36 to the supported gear 38comprises a yoke member 66 (Figures 3 and 4), which is adapted to be'clamped to the upper portion of the spindle 24 by means of a suitableclamping screw 62. Thisyoke member being positioned immediately above "anut 64, which is tightened against the base cylinder 86 to couple saidcylinder with the spindle '24. The yoke member 66 is formed integralwith aradial arm 66 provided with a longitudinal slot 68. A block 16 isadapted to be adjustably clamped to the arm 66' .by means of a bolt 12,which passes through the slot 68. The block 16 maybe radially adjustedby merelyturning a handle I4 connected withthe bolt I2. The upperportion of the block I6 carries a pin '16 which is secured in positionby means of a screw 16. This pin I6 is tapered at one end so as toproject within the space between the gear teeth, as indicated in Figure3. In this-manner any rotation expe-.v

rienced by the base-cylinderordrum 36 willflbe base 16 is a frame 86.This frame "is provided:

with a depending portion. 82, which carries "a rollbase I6. The upperportion of the frame 66' also carries an anti -i'riction roller 68,which is-adapt 0 ed to roll along the outer flat surface of a race bar86 secured to 'the upper portion of the base I6. The frame, 66- isformedwith a section ,92,

which can'ies a horizontally disposed race bar 84. This bar 64 iscompanion to and superim poses the bar 66, as clearly indicated inFigure 4- A plurality of ball bearings 96 are interposed be tween andform an anti-friction bearing for the bar 94, which bar is adapted to beshifted horiof the frame .66, and presents a friction surface I62, whichengages the peripheral surface of the base cylinder 36, It will thus beapparent that if the bar I66 is moved horizontally, rotation will beimparted to the base cylinder 36.

Horizontal movement may be imparted to the 'frame 86 by manipulating ahand-wheel I64 at the front end of the machine. This wheel I64 isconnected with a gear I66, which meshes with a larger gear I66, thelattergear meshing with rack teeth I I6 provided along the underside ofthe race bar 86. The race bar being stationary,

it will be apparent that when the gear I66 'rotates, horizontal movementwill be imparted to the frame.86.

An auxiliary frame or slide H2 is vertically slidable upon a guide II4of the frame 86. Vertical movement of this slide H2 is occasioned byturning a hand-wheel II6, which is coupled with a pinion or gear I I6meshing with rack teeth I26 formed within the guide .I I4 (Figures 2 and7). The upper portion of the frame II 2 is provided with alateralextension I22, which serves as a support for a contactor deviceI24.

This'contactor device I24 includes a central vertical shaft I26 securedbetween a pair of centers I28 and I 36 (Figure 4). The shaft I 26 formsthe support for an elongated member I32,'one end i of which presents aspherical element I34 adapted .to be engaged by a plunger I36 of a dialindicator I36. The opposite end of the elongated member I82 is recessedto provide a supportfor the contactor-proper I46. The contactor I46 maybe adjustably secured within the member I32 by means of a suitable setscrew I42. This contactor I46 is designed to engage the surface of theteeth 38a in the gear 36, as clearly indicated'in'Figures 1 and 4. Itwill be noted that the point of contact between the member -I46 and theteeth 36a is in proper alinement with the friction surface I62, whichengages the peripheral surface of the base cylinder 36. The mechanismfor effecting the vertical adjustment of the slide II2 serves to adjustthevertical position of the contactor I46 with respect to the -work tobe tested. It will also beseen that a yieldable set screw I43 (Figures 2and 7) is provided to positively secure the slide H2 in a position ofadjustment. From the foregoing it will be apparent that if rotation isimparted to the base cylinder 36 by the friction surface I62 'withoutslippage, andthe contactor is properly positioned with respect to thesurface ona toothi 36a, deviations, if any, from the true involutecontour will be indicated by the 'dial indicator I36.

" Attention is-now directed to the fact that the, dial indicator I36 ismounted upon an arm I44,

dial indicator I36 may be swiveled in such a manner that the indicatormay be reversed to contact on either side of the ball. It will be notedthat apair of pins I46 disposed on opposite sides of the elongatedmember I 32 (Figure 1) serve to limit the degree of movement of saidmember.

In order to correlate the degree of rotation with the readings madeonthe dial indicator I66, I

,93 9 I v v t made an indicator finger in (Figures -1, 4, and

'5). One end of the flnger I66 is formed with a pair of arms I60, whichare adaptedto frictionally engage within a peripheral recess I62(Figures pendlcular to the surface I02. should be distinguished fromdevices wherein the pressure is not exerted along astraight line asdescribed above. a

4 and 5) provided at the upper portion bf the v Obviously the inventionis not limited to the a sleeve 20. The finger I46 is provided with aslit Sp c fi t ill'al d tails. disclosed herein, but is I64 tofacilitate thetensloning of the arins or flncapable of othermodifications and changes withgers I60. The frictional engagementbetween out departing from the spirit and scope thereof.

the arms I50 and the adjacent periphery of the Having thus described myinvention, what I sleeve 20 is'sufllcient to securely hold the'fingerclaim asnew and desire to secure by Letters 10 in place, but is'sufficiently. impositlve to permit Patent is: the finger-to be manuallyshifted for purposes of l. A gear testing machine including a base, aadjustment; A suitable arcuate graduated scale. work supporting frameslidably supported on said I66,which indicates to a maximum of 40degrees, base, an indicator support slidable transversely 7 l5 iscarried by the slide I2. Before a test is started, of said work support,an indicator mechanism on the finger or pointer! is first moved'to thezero said indicator supportincluding a contactor for position asindicated in Figures 1 and 5. engaging the teeth of a supported gear,means .Attention is now directed to the means which movable with saidindicator support having a fric- I provide for maintainingfrictional'contact be tion surface, a cylindrical member corresponding.tween the periphery of the base cylinder 36 and in diameter with thediameter of the base circle 2 the friction surface I02. This mechanisminof the gear to be tested and rotatable as a unit cludes an auxiliaryslide I66, which is mounted with the gear to be supported, a mountingfor within the slide I2. The upper inner-portion of said cylindermember, and pressure applying the slide I66 carries an anti-frictionroller I60, means for maintaining frictional contact between whichengages the periphery of the base cylinder" said cylindrical member andsaid friction surface, 25 66 at a point diametrically opposite the pointsaid latter means acting on the periphery of said of engagement of saidcylinder withthe friction cylindrical member at a point diametrically.dpsurface I62. The roller I60 normally urged posite the point ofengagement of-said cylindrical into contact with the cylinder 66"through the member with said friction surface to thereby preagency of acoiled spring I62, which is interposed vent the transmission of pressureto the work 30 between a depending lug I66 of the slide frame suppor I56and-a sleeve I66, whlchls square incross-sec 2. A gear testing machineincluding a base,' a tion (see Figure 6). This sleeve I66 is threadedwork supporting frame slidably supported on said to receive companionthreads on a screw shaft base, an indicator support slidabletransversely I66 and is longitudinally. slidable within a recess -ofsaidwork s pport, an indicator mechanism I10 provided in the slide I2. Bymerelyiturning a j on said indicator-support including a contactorhand-wheel I'I2 mounted at the outer end ofv the for engaging the teethof a supported geanmeans threaded shaft I66, thes'leeve I66 may be movedmovable with said indicator support having a in either direction. Ifmoved to the left (Figure friction surface, acylihdrlcal membercorrespond- 40 4), the compressive action of the spring I62 upon ing indiameter with the diameter of the base cir-'- 4 the slide I66 "isincreased, cle of the gear to be tested and rotatable as a At thispointparticular attention is directed to unit with the gear to be supported,a mounting the' fact that the pressure exerted. to cause the for saidcylindrical member, and means for yield. 1 base cylinder 36 to, ineffect, roll on the straight ably maintaining frictional contact betweensaid friction surface I02 without slipping, is not transcylindricalmember and said friction surface,said 45 mitted through the bearings ofthe work, s pinlatter means'acting' on the periphery-or said eydie, butis transmitted directly through the cylinlindrical member at a pointdiametrically opp s te der 36 interposed betweenrthe bai- I06-and thethe point of engagement of said cylindrical 'memroller I60. By employingthe auxiliary antibet with said friction surface to thereby prevent itfrictionroller I60 as the means for imparting thetransmlssion of saidpressure tothe work pressure against the periphery of the basecylinsupport. I a der. 36, frictional contact is reduced to amini- ,3. Agear testing, machine including a base, a mum. That is to say,by'usingthe auxlliary roller work supporting frame slidably supported onsaid I60 contacting directly with the base'cylinder 26. base, anindicator support slldabie transversely diameterically opposite to thepoint of contact of said work support, an indicator mechanism on betweenthe cylinder and the frictionsurface, all said indicator supportincluding a contactorfor I strain on the bearingof the work spindle isreengaging the teeth of a supported-gear, means lieved. The roller Iisurged toward the cylinder movable with said indicator support having'a L through the pressure of the spring I62, and this friction surface,a cylindrical member correspond- 60 pressure-is transmlttedtothe pointof contact be a ing in diameter withthe diameter of the base 0 tween thecylinder 66 and the friction surface'l02. circle of the gear to betested and rotatable as a 3' Thus it maybe said that the base cylinderand unit with the gear to be supported, a mounting for the workarborbecome in a sense floating be said cylindrical member, and meansincluding a tween the roller I60 and the friction surface I02, rollerfor maintaining frictional contact between and aredependent on therotarybearlngsof the I said cylindrical member and said friction sur-(35 spindle for alinement purposes only. The bearing face, 'said rolleracting on the periphery'of said of the roller I60 has less friction thanthe bearcylindrical member at a point diametrically oping of thespindle, and therefore turns more freeposite the point ofengagement ofsaid cylindrical I 1y; In addition to-this, the roller I 60 may bemember'with said friction surface to thereby pre- 70 larger than thebase cylinder 36 when said base vent the transmission of said, pressureto thelwork 70 support.

4. A gear testing machine including a base, a work supporting frameslidablysupported on said base, anindicator support slidabletransversely of said work support, an indicator'mechanism on cylinder isused for a relativelysmall, gear. It will also be noted that the rollerI60 is located at the same height as the base cylinder and the frictionsurface. The pressure of the roller hearing is; therefore, in a straightline directly perbase transversely of said work support, anindisaidindicator support'including a contactor for engaging the teethof a supported gear, means movable with said indicator support having a.friction surface, a cylindrical member corresponding in diameter withthe diameter of the base circle of the gear to be tested and rotatableas a unit with the gear to be supported, a mountbase transversely ofsaid work support, an indicator mechanism on said indicatorsupportdneluding a contactor for engaging the teeth of a supported gear,a second indicator mechanism for indicating the degree of rotationexperiencedby the gear, means movable with said indicator support having-a friction surface, a cylindrical member corresponding in diameter withthe diameter of the base circle of the gear to be tested,

said cylindrical member movable as a unit with said work support andadapted in response to. en-' gage'ment with said friction surface toimpart rotationto a supported gear, a mounting for said cylindricalmember movable as a unit with said work support, and means for exertinga pressure against said cylinder to maintain frictional engagementbetween the cylinder and said frictional surface, said latter meansbeing constructed and arranged to exertsaid pressure withouttransmitting said pressure to the work support, whereby to I precludethe introduction of errors which might otherwise occur.

6. A gear testing machine including a-base, a work support horizontallymovable on said base, an indicator support horizontally movable'on saidcator mechanism on said indicator support includinga contactor forengaging the teeth of a supported gear, a second indicator mechanism forindicating the degree of rotation experienced by the gear, means movablewith said indicator support having a friction surface, a cylindricalmember corresponding in diameter with the diameter of the base circle ofthe gear to be tested, said cylindrical member movable as a unit withsaid work support and adapted in response to engagement-with saidfriction surface toimpart rotation to a supported gear, a mounting forsaid cylindrical member movable as a unit with said work support, andmeans 'actingdirectly upon the cylindrical member at a point disposeddiametrically opposite the point of engagement of said member with saidfriction surface to maintain frictional. engagement between the partswithout transmitting said pressureto the work support.

' an indicator mechanism on said indicator sup-'- port including acontactor for engaging the teeth of asupported gear, a second indicatormecha-' nism for indicating the degree of rotation experiencedby thegear, means movable with said indicator support having a frictionsurface, acylindrical member corresponding in diameter withithe diameter.of' the base circle of the gear to be tested, said cylindrical membermovable as a unit with said work support and adapted in response toengagement with said friction surface to impart rotation to a'supportedgear,'a mounting for said cylinder member movable as a unit with saidwork support and means including a roller directly engaging theperiphery of said cylindrical member at a pointoppositely disposed fromthe point of-engagement of said cylindrical member with said frictionsurface for exerting pressure to maintain frictional contact between thecylindrical member and friction surface.

8. A gear testing machine including a base, a work support slidablymounted upon said base, said support including a spindle for carrying agear to be tested, an indicator support slidable on said basetransversely with respect to the work support, an indicator mechanism onsaid indicator support including a contactor for engaging the teeth of asupported gear, means movable with saidindicator support having afriction surface, a cylindrical member' corresponding in diameter withthe diameter of the base circle of the gear to be tested, saidcylindrical member being movable as a unit with said work support andadapted in response to engagement with said friction surface to impartrotation to a supported gear, amounting for said cylindrical member tainthe frictional contact between said cylindrical member and said frictionsurface.

9. A' gear testing machine including a base, a work support slidablymounted upon said base, said support including a spindle for carrying agear to be tested, an indicator support slidable on surface, acylindrical member corresponding in diameter with the-diameter of thebase circle. of the gear to be tested, said cylindrical member beingmovable as a unit with said work support and adapted in response toengagement with said .friction surface to impart rotation to a supported:member and said friction surface, and yieldable means for urging saidauxiliary support in a direction to maintain contact between thecylindrical member and said friction surface. I

10. A gear testing machine includinga base, a work support slidablymounted upon said base, said support including a spindle for carrying agear to be tested, an indicator support slidable on said basetransversely with respect to the work support, an indicatormechanism onsaid indicator support including acontactor for engaging the teeth ofa'supported gear, means movable with said indicator support having afriction surface, a cylindrical member corresponding in .di-

ameter with the diameter of the base circle of being movable as a unitwith said work support and adapted in responselto engagement with saidfriction surface to impart rotation to a supported thegear to be tested,said cylindrical member t auxiliary support slidably mounted within thework support, means carried by said auxiliary support. adapted to actdirectly against the pe- "ripheryof said'cylindrical member to maintainthe frictional contact between said cylindrical member and said frictionsurface, yieldable means vfor urging' said auxiliary support in, a,direction to vmaintain contact between the cylindrical member and saidfriction surface, and means for adjustably controlling the force exertedby said yieldable means.

' nism having an intermediate pivot, the

assembly ofthe pants; n

machine including abaseh 11. A gear testing machine including a base, awork support'mov'able on saidbase for carrying a gear to be tested, anindicator support movable on saidbase transversely of said work support,an indicator mechanism on said support including a contactor forengagingthe teeth of a su'pported gear, said contactor comprising alever mechaconta tor proper being positioned on one side of said p vetand a ball member on the opposite side adaptedfor engagement with theactuating'member of an indicator, and an indicator equipped with anacthrough the center of said ball whereby to enable said indicator to beshifted from one side of the.

contactor to the other without necessitating dis- 12. A gear testing awork support movable, on said base for carrying a gear to be tested, anindicator support movable on said base transversely of said worksupport, an indicator mechanism on said support including a contactor.for engaging the teeth of a supported gear, said contactor comprising alever mechanism having an intermediate pivot, the contactor proper beingpositioned on one sideof said pivot and a ball member 'on the oppositeside adapted for engagement with the actuating ,member of an indicator,and an indicator equipped with, an auxiliary support for carrying theindicator, saidsupport'being swivelly mounted about an axis passingthrough the'ball of the contactor whereby to enable said indicator to bev 13. A gear testing machine including a work support, an

shifted to opposite sides of the contactor.

support, an indicator support, said work support and indicator supportbeing relatively f shiftable,

an indicator mechanism on said indicator support .including a contactorfor engaging the teeth of a gear carried by the work support, meanshaving a plane friction surface associated with one of said supports,. aroller having a peripheral friction surface associated with the other ofsaid supports, a cylindrical, member corresponding in diameter with thediameter of the base circle of the gear to be tested, and rotatable as aunit with a gear carried by the work support, said plane frictionsurface and peripheral friction surface engaging the periphery of saidcylindrical member at diametrically opposite positions,'the

relative shifting between the work support and indicator support servingto cause rotation of said cylindrical member, and means for urging.

at least one of said friction surfaces into engagement with theperiphery of said cylindrical member without subjecting a supported gearto lateral displacement. d I

14. A gear testing machine including a work indicator support, said worksupport and, indicator supportbeing relatively shiftable, an indicatormechanism on said indicator sup-.

port including a contactor for engaging the teeth of a gear carried bythe work support,

means having a plane friction surface associated with one of saidsupports, a roller havinga peripheral friction surface associated withthe other. of said supports, a cylindrical member correspending indiameter with the diameter of the base circle of the gear to be tested,and rotatable as a unit with a gear carried by the work support, aspin'dle providing a mounting for said cylindrical member, the axisofwhich is positioned friction surfacesproviding an. abutment, and.

means forurging the other friction surfacetoward the abutment surfacewhereby to prevent the transmission of forces which would have atendency to laterally displace a supported gear. 15. Agear testingmachine including a work support, an indicator support, said worksupport and indicator support being relatively shiftable, an indicatormechanism on said indicator support including a contactor for engagingthe teeth tuating member engageable with said ball, said indicatorswivelly mounted about an axis passing of a gear carried by the worksupport, means having a plane friction surface associated with one ofsaidsupports, a roller having a peripheral friction surface associatedwith the other of said supports, a cylindrical member .corresponding indiameterwith the diameter of the base circle of the gear to be tested,and rotatable as a unit with a gear carried by the work support, saidplane friction surface and. peripheral friction surface engaging theperiphery of said cylindrical memher at diametrically oppositepositions, the relative shifting between the work. support and lndieator support serving to cause rotation'of said cylindrical member, andmeans for urging said peripheral friction surface into engagement withthe periphery of said cylindrical member, the

work supporting frame mounted on said base, a-

spindle rotatably supported by said frame; a cyoppositely disposed planesurface providing an 7 abutment whereby the pressure thus applied tolindrical member corresponding in diameter with thediameter of the basecircle of the gear to be tested, said cylindrical member being mountedupon and rotatable with said spindle, means providing a coupling betweensaid spindle and the gear to be tested whereby to cause said cylindricalmember and gear to rotate as a unit, an indicator support,

able,

said indicator support and work supporting frame being relativelyshiftan .indicator mechanism on .said' indicator support including acontactor for engaging the teeth,. of .a supported gear, means coupledwith said indicator support having a to W friction surface, saidfriction surface being adapted to contact the periphery of saidcylindrical member, a member having a friction surface adapted to engagethe periphery of said cylindrical member at a position diametricallyopposite to the point of contact between'said cylindrical member andsaid first mentioned friction surface, one of said friction surfacesproviding an abutment, and means for urging the other frictionsurfaceinto engagement with the periphery of said cylindrical member and in adirection toward the oppositelydisposed friction CARL G. OLSON.

